Shadow Monsters by Philip Worthington is another amazing interactive game / art work. Philip has worked with Sony in the past with their Eye Toy. Take a look at Ants and Line Riders at his site too. Fantastic! Many thanks to Richard Van Tol of GameAccessibility.com for the initial link.

"The computer sees a silhouette of your hand, and analyses its curves and contours," says Philip. "By looking at the gaps in-between your fingers, and where they're pointing, it knows what kind of puppet you're making." It is bit like watching a cartoon, as animated teeth and hairs dance around the silhouette to a tune of squeaks and buzzes.